Treatment of metals



April :21, 1942. w. BRIDGES TREATMENT OF METALS Filed July 10, 1940 Fig.1.

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Jim/neg April 21, 1942.

Filed July 10, 1940 Fig. 4.

W. BRIDGES TREATMENT OF METALS 5 Sheets- Sheet 2 April 21, 1942. w D s I 2,280,470

TREATMENT OF METALS Filed July 10, 1940 5 Sheets-Sheet 3 I W; L5 13? l 23 k J k 23 by s ' I Atto iy TREATMENT OF METALS Filed July 10, 1940 5 Sheets-Sheet 4 In uenl'or April 21-, 1942. I w, m s 2,280,470

TREATMENT OF METALS Filed July 10, 1940 5 Sheets-Sheet 5 Fig. 5.

- bra/enter Walterfiridges,

Attorney Patente pr. 21, 1942 TREATMENT. OF

x TALS Walter Bridges, Chelsea, London, England Application July 10, 1946, Serial No. 344,811

In Great Britain July 12, 1939 7 Claims.

The invention relates to the heat treatment of metals and is more particularly concerned with the hardening, tempering, quenching or cooling of heated metals. The invention is especially applicable to the treatment of steel billets wherein they are heated and cooled for the purpose of producing the physical properties desired during or after forging operations.

A particular application of the invention is to piercing projectiles.

It has been the practice in certain instances, v to heat the steel billet to a high temperature and to immerse the same in oil as a cooling or quenching medium. In this process considerable inconvenience has been caused when the temperature of the bil et has been raised in excess of that at which the oil will fire. In those cases where the billet is only partly immersed in the oil there is a grave risk of the oil being fired by the heat of the un-immersed part of the billet. The main object of the present invention is to overcome the aforesaid difficulty and to ensure that in such circumstances the oil does not fire.

The present invention provides in the treatment of a billet or the like of metal (hereinafter referred to for the sake of convenience as a billet) a method or step of wholly or partly immersing said billet in oil in an atmosphere wholly or substantially devoid of oxygen. A feature of the present invention resides in utilising the heat of the billet for consuming the oxygen in said atmosphere. In carry-ing the invention into effect there may be employed a container which at its lower end affords access of the oil to the billet and at least during the immersion and preferably also prior to it the said lower end is sealed by the oil itself. For this purpose after the billet has been enclosed in the container, the two are lowered towards the oil until the seal is effected and the heated billet is further lowered within the container to effect the immersion. Alternatively, the billet and container may remain stationary whilst the oil (located in a drum or the like) is moved relatively thereto.

In a further alternative there may be employed a container that is open at the top and bottom and has its bas immersed to effect the seal and the heated billet is lowered into the container, the top of the latter is closed, and the immersion is then effected.

Whichever method of immersion is employed cool oil is advantageously supplied to the region of immersion.

carrying out the aforesaid treatment comprising an oil tank, a container forthe billet, occupying or "movable to occupy a position at which its lower end is immersed, and a billet support within the container which support is movable within the container to immerse the billet.

In order that the invention may be better understood reference will now be made to the accompanying drawingsin which Figure 1 is a sectional elevation of one apparatus for carrying out the invention.

Figures 2 and 2a are sectional views on a larger scale of the container showing a number of billets immersed.

Figure 3 is-a plan thereof, partly in section.

Figure 4 is a fragmentary sectional elevational view illustrating one of the clamps which may be employed for retaining the container cover in place.

Figure 5 is a section similar to Figure 1, but showing a modified form of the invention, and

Figure 6 is a fragmentary sectional elevational view illustrating a modified means for suspending the billets or projectiles.

The invention will be described as applied to the heat treatment of armour-piercing projectiles following which description its applica- -tion to other billets will present no difficulties.

In th exercise of this invention employing the apparatus shown in Figures 1 to 4 there is a tank Hi provided at its upper. open end'with a supporting structure indicated at I ll. This struc-- ture may comprise two parallel angle irons ill" and two stays ltl' at right angles thereto. By means of bolts indicated at B the height of the structure relatively to the tank may be varied. The tank is filled to level L with oil. At the top of this tank a container ll open at the top and bottom is supported by said structure l0 and projects upwardly therefrom and downwardly therethrough so that its lower end is immersed in the oil to make an oil seal. The projectiles l2 prior or subsequent to their wtlhdrawal from' the furnace wherein they are treated are fastened to a carrier or spider l3 from which they are suspended, this spider l3 being. of the skeleton form best shown in Figures 2 and 3. For examlid Him the container H is slidably received.

The loaded carrier is brought over the open top of the container and is then lowered by means of the. lifting tackle I! so that the carrier enters the container H. In its downward passage the lid or closure l9 comes to rest on the top of the container and so closes it, a number of inclined projections being provided arou. .d the top of the container for guiding the lid [9 to the' .correct attitude. The said lid may be clamped in tainer H) which is completely sealed except for certain outlets 22 provided in the lid for the escape of the products of combustion. These outlets are desirably covered with wire gauze 28*. Since the volume of air within the closed container is comparatively restricted the heat of the projectiles deprives said air of oxygen by a, proc-' ess of combustion' Continued downward movement of the carrier I3 subsequent to the closure of the lid i9 carries the projectiles down through the inert atmosphere in the container until they are partially immersed in the oil as illustrated in Figure 2. At this stage the carrier comes to rest on a ring 23 supported on suitable projections 23' placed to receive it inside the container. The height of the projections 23 may be adjustable to vary the depth to which the billets are immersed or alternatively the depth to which the billets are immersed is varied by the bolts B which as previously stated vary the height of the structure l0 relatively to the height of the tank [0; if desired the billets may be totally immersed.

The projectiles remain immersed until they are cooled to the required temperature and during the process of immersion and subsequent cooling (particularly during the initial stage of cooling) the oil is subjected to very considerable .heat which results in partial vaporisation. The

oil vapours rise up the container l I but by virtue of the fact that such chamber is wholly or partially denuded of oxygen for the reasons stated the vapours are not ignited and the oil does not fire; the vapours exude to atmosphere through the gauze covered outlets 22, the effective size of which may if desired be adjustable.

During the immersion process it is preferred to supply cool oil to the region of immersion.

For this purpose an oil tank (not shown) is provided with, an outlet pipe 24 having a vertical branch 25 which leads by way of a cock 26 to a baffle 21 located immediately below the oil level L at a position centrally of the container l I. The oil under the action of gravity or a suitable pump in the pipe line passes by way of the open cock 26 and pipe line 25 and rises upwardly to the baffle 2'! which functions to spread the oil outwardly. This ensures that the oil in this'region is always kept fairly cool. The tank I!) may be filled from the pipe 24 through another cook 28.

In the apparatus illustrated in Figure 5 there is employed a container H which is separate from the tank l0 and has its top closed, said top being provided with small outlets 22,-which are preferably covered with wire gauze. The comcollar 32' and boss 22'.

that, as in the first example, the immersion of,

plete container is slidably mounted on a rod 23 suspended from lifting tackle l1 capable of being traversed along a gangway (not shown). The projectile or projectiles either prior or subsequent to removal from the furnace is or are attached to a carrier 30. In Figure 5 a single projectile is shown as being thus attached. This carrier is secured by means of a hook 3| to the lower end of the rod 29 with the container II in a raised postiion, whereafter and preferably immediately prior to immersion the container is lowered so that the projectile is enclosed therein as is illustrated in chain dotted lines at the lefthand side of Figure 5. This relative movement of the container H on the rod 29 may be effected by means of a cable or the like 32 held by the hand or secured to the container when it is desired to hold the latter in a raised position on the rod 28.

The projectile having itself been enclosed'in the container its heat subsequent to such enclosure tends to denude the atmosphere within the container of oxygen especially after the container central portion, which thus forms a supporting cradle lOa for its reception, and a limit for its downward movement. The container then occupies the position best illustrated in Figure 5. Continued lowering of the rod 29 relatively to the container results in the projectile being lowered within the container until it is immersed in the oil. The extent to which the projectile is immersed in the oil is preferably variable and may readily be determined by controlling the extent of downward movement of the rod 29. To this end a collar 32' is formed at the upper extremity of such rod or is otherwise conveniently located thereon and an upstanding boss 22' is formed exteriorly of the top of the container ll. After the container in its downward movement has come to rest on the cradle l0 9. distance piece 33' of predetermined length is inserted between the collar 32 and the boss 22' so thatv as the rod 29 is lowered the said distance piece is wedged between the collar and boss and the downward movement of the rod is arrested. It will thus be seen that by using distance pieces of different length the extent of the downward movement of the rod 29 and therefore the extent to which the projectile extends beyond the skeleton crade I ti and is immersed in theoil is varied. Each of the distance pieces 33' may conveniently be of U section so that they embrace the rod 29 when positioned between the It will be appreciated the heated projectile takes place in an atmosphere which is substantially devoid of'oxygen with the advantageous results hereinbefore set forth. f

The projectile may be secured to the carrier 30 in any suitable manner; for example the carrier may be provided with a lazy-tongs or toggle adapted to be expanded in the interior of the pro-' jectile. In the construction shown in Figure 5 a cross-piece 36 is pivoted to the carrier and whensaid cross-piece is received in the projectile one end of it engagesan annular recess or groove in the interior of the projectile and the other end of it wedges against the interior peripheral wall of the projectile, sov that the projectile is itself flrmly suspended.

Other means for attaching the projectile to the carrier may be employed. In particular a small employed irrespective of whether one or a plurality of projectiles is attached to each carrier and irrespective of which of the methods of immersing the projectile in the oil is employed.

The foregoing embodiments of the invention are described merely by way of example and are not to be construed in a limiting sense; numerous other embodiments within the scope of the appended claims may be employed.-

I claim:

1. In the heat treatment of metal billets wherein the billets are heated and then at least partially immersed in oil, the method of preventing ignition of the oil by the heat of the billets which comprises surrounding the heated billets with an air-containing enclosure; .impoverishing the air within said enclosure by combustion; and efiecting the immersion of the billets in the oil in the presence of such impoverished air.

2. In the heat treatment of metal billets wherein the billets are heated and then at least partially immersed in oil, the method of preventing ignition or flashing of the oil by the heat of the billets which comprises materially reducing the oxygen content of the air immediately surrounding the heated billets by combustion induced by the heat of the billets; and effecting the immersion of the billets in the oil in the presence of the impoverished air.

3. In the heat treatment of metal billets wherein the billets are heated and then at least partially immersed in oil, the method of preventing ignition or flashing of the oil by the heat of the billets which comprises segregating the air adjacent the heated billets from. the surrounding atmosphere, whereby combustion induced by the heat of the billets will impoverish such segregated air; bringing said impoverished air into the projectiles to the carrier may of course be proximity to the oil; and efl'ecting the immersion of the billets in the oil in the presence of said impoverished air.

4. In the heat treatment of metal billets wherein the billets, subsequent to heating. are at least partially dipped into an oil bath, the meth- 0d of, preventing ignition or flashing of the oil by the heat 01' the billets which comprises mantling the billets in an enclosure having an open lower end, whereby the heat of the billets will effect a material reduction in the oxygen content of n the air in said enclosure; immersing said open end of the enclosure in the oil bath to provide a restricted area 01 contactbetween the surface of the oil and the impoverished air in the enclosure; and dipping the billets into the oil within said restricted area.

5. A treatment according to claim 1, wherein the enclosure for the billets has an open top and an'open base adjacent the oil surface and the heated billets are lowered into said enclosure poverish the restricted volume of air in said conthe heated billet in the blanketed oil.

'7. In the heat treatment of a billet of metal, wherein the billet subsequent to heating is at least partially submerged beneath the surface of an oil bath, the process for the preventionof ignition or flashing of the oil due to the heat of, the billet upon said submersion, which comprises heating the billet; then introducing it'into a relatvely cold mantle of restricted volume containing air, whereby the heat of the billet will impoverish the air in said mantle to an extent insufllcient to support combustion or flashing of the oil 01' the bath without raising the temperature of the mantle above the flashpointof the oil; blanketing the surface of the oil by said impoverished atmosphere; and eflecting said submersion through the blanketed 011 surface.

- WALTER BRIDGES. 

